Recently, as the integration and the density of a semiconductor device becomes higher, the wiring of a circuit gets increasingly miniaturized, and the number of layers in a multi-layer wiring also increases. In order to implement the multi-layer wiring while miniaturizing the circuit, it is required to precisely flatten the surface of the semiconductor device.
As a technology of flattening the surface of a semiconductor device, a chemical mechanical polishing (CMP) has been known. A polishing apparatus configured to perform the CMP includes a polishing table to which a polishing pad is attached, and a top ring configured to hold a polishing target (e.g., a substrate such as a semiconductor wafer, or various films such as a metal film or a barrier film formed on the surface of the substrate). The polishing apparatus supplies an polishing abrasive liquid (slurry) to the polishing pad, and presses the polishing target held by the top ring against the polishing pad while rotating the polishing table so that the polishing target is polished.
In the polishing apparatus, a polishing end point is generally determined in order to polish the polishing target to a desired thickness. For example, in the related art, a thickness detection of a conductive film is performed using an eddy current-type film thickness sensor. However, it is difficult to immediately terminate a polishing process at a point in time when a target thickness is reached. This is because a detection delay time occurs when a film thickness is detected, and it takes a certain period of time to stop polishing of a conductive film in actuality. Therefore, in a polishing process known in the related art, a polishing speed is calculated, and a temporary end point film thickness obtained by adding a predetermined offset value to a target thickness at which stopping the polishing is desired in actuality is calculated from the polishing speed. After the temporary end point film thickness is detected, the conductive film is polished for a predetermined polishing time. See, for example, Japanese Patent Laid-Open Publication No. 2015-076449.